I am currently using E. coli as a vector to generate copies of a plasmid that we plan to insert into Myxococcus xanthus. Is it important to adjust the pH of LB from 6.85 (which is what it is when we make it) to between 7.07.4?
Don't do it, it is a waste of time. LB is unbuffered.
We used to adjust pH around neutral just with pH-indicator paper (before autoclaving), which obviously is not too accurate. I think anything close to 7 should be OK for bacteria. I found an interesting summary online.....
https://www.usc.edu/CSSF/History/2008/Projects/J1429.pdf
Hi, I agree with Manoj. I never adjust the pH of LB and E. coli is growing perfectly. On general, when mixing correctly all LB compounds you have more-less neutral pH .
Since LB is not buffered, you can save the time (and ressources) for this step. The pH is close to 7 anyway and the metabolic activity of the bacteria will change this very fast.
It's pretty common for LB (and similar) media recipes to recommend increasing the pH to be somewhat basic (usually 7.5 or 8.0). Probably this is useful if you're trying to grow to high cell densities (or maintain exponential growth longer) to delay media acidification somewhat. But, no, it's not usually necessary.
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